WHEN it comes to savage performance from a soft-top, things don't get much quicker than the new Mercedes SLS AMG roadster.

The much-awaited stablemate to the SLS Coupe can blast into the atmosphere in a fleeting 11 seconds - and that's just peeling back the fabric roof.

With a 6.2-litre V8 engine producing a massive 563bhp beneath the bonnet, the supercar has the potential for a top speed of 197mph.

It will make its debut at the Frankfurt Motor Show in September before hitting the streets later in the autumn.

Mercedes says both SLS models were created in parallel but the engineers devoted special attention to the roadster's driving dynamics, bodyshell rigidity and soft top.

Our pictures show slightly disguised versions of the car - there's black adhesive foil at the front, rear and along the sides - with its trademark long bonnet, large wheels and a short rear end.

Because there are no gullwing doors - like on the coupe - and a fixed roof, the roadster has thicker, more robust side sills.

And in order to achieve handling dynamics identical to those of the Coupe, the roadster has two features designed to increase bodyshell rigidity.

The cross-member carrying the dashboard has extra supporting struts and a mounting stay between the soft top and the fuel tank makes the rear axle even more rigid, preventing vibration.

The car has already been extensively tested in the most inhospitable regions of the world.

In Laredo, Texas, for example, there is a particularly fine dust which finds its way into practically any gap - and tests the seals to the limit.

And a soft-top endurance test has comprised 20,000 closing cycles on a stationary rig plus 2,500 closing cycles while on the move.